The effects of nutritional status of rats upon several aspects of their lung connective tissue metabolism will be investigated. Normal rats or mice will be subjected to caloric deprivation, protein deprivation, and to diets deficient in Vitamin B6 (pyridoxine), in copper, and in iron. They will also be fed diets supplemented with ascorbic acid (Vitamin C), with penicillamine, or with homocysteine. Other rats will be fed the same diets and subjected, in addition, to exposure to various pneumotoxins that provoke acute pulmonary fibrosis. Connective tissue-related parameters to be evaluated in the rodent lungs include: Collagen content, collagen synthesis rate, total protein synthesis rate, collagen crosslinking, elastin turnover, and elastin synthesis. These studies should provide us with a data base from which to evaluate the role of nutritional status of animals upon various parameters related to connective tissue metabolism of normal lungs and of fibrotic lungs.